Deere 404-466-619 cranckshaft regrind

fdt860

Well-known Member
I have been told in France by few machinists that the crank on Deere motors should not be grinded, as it will break. I have heard of at least 2 cases like this, on a 8640 and a 4440.
They said the hardening is not deep enough and you have to harden them again. Deere is selling shells to put on regrind cranks, so that makes me wandering if they are thrue.

I read on other sites than the key to regrind was the fillet. And also that the grinding was work hardening the crank.
So what do you do on Deere cranks that are slightly bad?
What should be the fillet size on a 466 crank?
How much have you grind them with success?
Last, are the Deere cranks cast iron or forged steel?
Can I buy FP-Diesel cranks, Mahle Clevite, original John Deere (i cannot pay that) ?

Thanks!
Frederic
 

As you stated the usual cause of the break is a botched job of maching the radius between the new journal surface and the crank throw.
 
I could not help but share a memory about a bad harmonic balancer. A former neighbor, who was and still remains a Big Time Operator (BTO) and has gone through at least 2 "high debt" related "financial restructurings" back in the 1980's and 1990's, had a large, four wheel drive tractor on his farm. He stopped into the place where I was working at the time and was telling us about his tractor. He and his family members noticed a vibration when the engine speed was above a certain rpm. This vibration grew worse as the fall progressed. They all were aware of this, and continued to slow down the engine until it quit vibrating, and ran it all fall until tillage was complete. The day after they finished the fall tillage, they were moving the tractor from one farm to the home place and the crankshaft broke just behind the harmonic balancer. The tractor had been off warranty for quite some time. He was intent on seeking compensation from the tractor manufacturer or the engine manufacturer for the hefty bill he was about to face, as he thought the company should stand behind it. I do not know what the ultimate outcome was, but the lack of any sort of common sense, and perhaps some arrogance on his part for thinking the company should stand behind this was appalling. Just another example of the sense of entitlement we have in this country and so many people who want something for nothing!
 
In the case of the 8640, the crankshaft broke at the rear main 5hr after complete out of frame overhaul with reground crank.. (well, it is an 8640, so it has to be out of frame). Anyway, a big bill and the engine never ran again... THey put a chopper engine in it and readjusted the injection pump to get the torque back up of the tractor engine.

So from your experience, grinding is OK?
 
Grinding to .20 under is okay, it's up to the machine shop to keep the radial dimension on the edges,,no problem around here,, in the 8640 the block probably flexed during an extreme oscillation..meaning the front end leaned up against the frame stop a bit too hard, this was /is a common issue on those models..this will break the crankshaft..a worn balancer is not so common to break a crank,,not saying it won't, but I have removed a lot of very worn ones on 4020's and the crank was still alive..
 
Well what your being told is exactly the opposite of what the machinist tell my around here. They find surface cracks with cheap magna flux style test equipment on JD cranks shafts as the crankshafts are harder. The surface cracks are "false" readings on the crankshaft's true condition.

I have seen very few JD crankshafts fail because of faults in the crankshaft itself. The failures are usually balancer or block issues. The older JD articulated tractors crankshafts failed because of strength issues in the engine block. The front axle pivot/mount put high stress loads on the engine block itself.

I find it funny how people run down the quality of JD products. I know first hand that JD goes to great lengths to provide HIGH quality components in their equipment.

Maybe the French fellows are talking about the engines built in the SARN France plant!!!!! ???? LOL

The JD crankshafts are forged steel. I have net seen a cast Iron crankshaft in any modern equipment built in the last fifty years.

Post this question down on the tractor puller forum. I know of JD factory crankshafts that are turning double the RPMS and 5-6 times the factory horsepower. They are not breaking very often at these levels.
 
Thank you for your inputs.
No, we are talking US cranks. For the Saran built ones, they are so cheap that you just put a new one. Probably, the right answer would have been to line bore the crank every time there are failures with the mains.

Deere is putting cast crank in their 8.1L engines with rolled radius and powertech engines. I should have been smarter and look at this picture:Difference between a forged and a cast crank is obvious. Those cast cranks cannot be ground...

http://www.reliancepowerparts.com/c...tins/john-deere/crankshafts/REL-JD1.30-15.pdf

I have a 5720 chopper crank home that has been ground but never installed, I will inspect the radius thoroughtly with a radius checker.
 
(quoted from post at 15:48:23 05/17/17) Thats just bull any machine shop worth there salt knows how to machine a crank

Agreed, that's why I questionned it. I can tell you shops in Europe are hard to find compared to US. Even servicing a RoosaMaster is an issue. You better have the know how yourself and know how to bring parts from the US.
 
And their lies the whole problem The machine shop that's worth their salt in many areas is closed up and gone, The old guy retired or dropped dead one day. The younger ones weren't interested in learning the skills to fix old stuff in the modern throw away replace it world.
I got a crank here from a fordson I brought with a rebuilt motor, The local shop ground it and it broke as they ground a gas crank radius on a diesel.

I don't rebuild customer motors anymore as the fantastic machine shop 3 hours round trip away closed, I don't want to put my name on bent or incorrectly ground cranks in my customers jobs from other local shops that they are famous for producing. A friend of mine knows a good machinist 12 hours round trip from here. Anything personal I want machined will probably go there so I know it's right when it comes back, customers just won't pay the extra costs to use him that far away, so it would just be my headache from the local guys.
 

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